"item_durability_changed" does not trigger when shears are used to shear animals

Cannot confirm, it's working fine for me, using this whole advancement :

{
    "criteria": {
        "used": {
            "trigger": "minecraft:item_durability_changed",
            "conditions": {
                "item": {
                    "item": "minecraft:shears"
                }
            }
        }
    },
    "rewards": {
        "experience": 100
    }
}

Make sure the durability of the shear actually change and that the advancement is not already granted, otherwise the advancement will not trigger.

This exact advancement only triggers when a block is broken using the shears but not when an animal is sheared.

{
    "display": {
        "icon": {
            "item": "minecraft:shears"
        },
        "title": {
            "translate": "advancements.husbandry.use_shears.title"
        },
        "description": {
            "translate": "advancements.husbandry.use_shears.description"
        }
    },
    "parent": "minecraft:husbandry/root",
    "criteria": {
        "used": {
            "trigger": "minecraft:item_durability_changed",
            "conditions": {
                "item": {
                    "item": "minecraft:shears"
                }
            }
        }
    }
}

Still cannot confirm when using your provided file, you should provide a more detailed step by step reproduction of your issue, like how you get your shear, your sheep, where your advancement file is, how you manage your advancement testing with /reload, grant and revoke, and any relevant informations.